Efficient NO2 sensing performance of a low-cost nanostructured sensor derived from molybdenite concentrate

Accumulation of industrial solid waste necessitates the development of utilization processes and technologies to reduce their negative environmental impact. Herein, molybdenite concentrate from the mining-metallurgy industry is systematically characterized as a valuable starting material for the fabrication of an efficient and low-cost nanostructured gas sensor. Few-layer MoS2 is obtained from molybdenite concentrate by liquid nitrogen exfoliation and deposited on different substrates by spin coating and drop casting. It is found that spin coating is advantageous over drop casting in fabricating a homogeneous and dense few-layer MoS2 film. The charge-transfer-based sensing performance of the fabricated few-layer MoS2 film is investigated upon exposure to NO2 at different temperatures (50, 100, and 120 °C). At an optimized temperature of 120 °C, a faster recovery is achieved, and the fabricated device exhibits 28, 38, and 44% sensitivity to 10, 50, and 100 ppm NO2, respectively, making it suitable for practical applications. Furthermore, the adsorption affinity of NO2 to the predominant (002) crystallographic plane of MoS2 is estimated from the distribution of field density and the calculated differential adsorption energies. According to the molecular modeling data, NO2 in the Ar/NO2 mixture has better interaction (dEad/dNNO2 = 4.77 kcal mol−1) with the few-layer MoS2 surface than individual NO2 (dEad/dNNO2 = 2.57 kcal mol−1), and van der Waals interaction (≈14 kcal mol−1) is the main adsorption force compared to the relatively weaker electrostatic interaction (<1 kcal mol−1). This work demonstrates a straightforward approach not only for the conversion of molybdenite concentrate into an efficient and low-cost nanostructured gas sensor but also for the reduction of the negative impact of accumulated molybdenum concentrate on the environment and human health.TU Berlin, Open-Access-Mittel – 202

Gazsimon atsetaldegidni bi2wo6 tomonidan modifikatsiyalangan ZnWo4 fotokatalizi orqali uv nurlanish ostida fotokatalitik parchalanish mexanizmini o’rganish

Indoor air quality has a significant impact on human health as people spend more time indoors. As a common indoor air pollutant, acetaldehyde is considered toxic when exposed to it for a prolonged period. The aim of this study is the enhancement of the photocatalytic activity of ZnWO4 with a monoclinic wolframite structure for degradation of gaseous acetaldehyde by modifying its surface with Bi2WO6 layered structure. The mechanisms behind the enhancement photocatalytic activity and the pathways for acetaldehyde photodegradation over the Bi2WO6-modified ZnWO4 photocatalyst are discussed.Fil: Hojamberdiev, Mirabbos. National University Of Uzbekistan; UzbekistánFil: Vargas Balda, Ronald Eduardo. Universidad Nacional de San Martin. Instituto Tecnologico de Chascomus. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - la Plata. Instituto Tecnologico de Chascomus.; ArgentinaFil: Daminova, Shahlo S.. National University Of Uzbekistan; UzbekistánFil: Kadirova, Zukhra C.. Tashkent Chemical-technogical Institute; Uzbekistá

Unraveling the photoelectrochemical behavior of Ni-modified ZnO and TiO2 thin films fabricated by RF magnetron sputtering

Zinc oxide (ZnO) and titanium oxide (TiO2) thin films are fabricated by radio frequency magnetron sputtering, which allows fine control of the properties and compositions of semiconductor materials with practical application in solar-light-driven water splitting. Here, nickel is introduced as an effort to engineer the band structures and to enhance the photoelectrochemical performance of the TiO2 and ZnO photoanodes. An increase in the Ni concentration changes the preferred orientation of ZnO crystals and inhibits an anatase-to-rutile phase transformation in TiO2. Pristine ZnO and TiO2 thin films have columnar structures with average widths of 200 nm and 50 nm, respectively, and an increase in the Ni concentration reduces the width of the columnar structures. The results from X-ray photoelectron spectroscopy analysis reveal that Ni2+/Ni3+ ions are successfully introduced into the ZnO and TiO2 lattices, and oxygen vacancies are formed. The effect of Ni is also studied by Mott-Schottky analysis, Gärtner theory, and open circuit potential decays, revealing important changes in the optoelectronic features of the TiO2 and ZnO photoanodes. Enhancement in the photon absorption is integral for the higher activity in Ni-modified TiO2, whilst an efficient collection of charge carriers is rather determining in Ni-modified ZnO. In addition, the interaction of water molecules with the surfaces of pristine and Ni-modified ZnO and TiO2 thin films is explored using molecular modeling. Tailoring the optoelectronic properties through a suitable fabrication protocol can lead to efficient and cost-effective light-harvesting materials.Fil: Hojamberdiev, Mirabbos. Technishe Universitat Berlin; AlemaniaFil: Vargas Balda, Ronald Eduardo. Universidad Simón Bolívar; Venezuela. Universidad Nacional de San Martin. Instituto Tecnologico de Chascomus. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - la Plata. Instituto Tecnologico de Chascomus.; ArgentinaFil: Bhati, Vijendra Singh. Indian Institute of Technology Jodhpur; IndiaFil: Torres, Daniel. Universidad Simón Bolívar; VenezuelaFil: Kadirova, Zukhra C.. National University of Uzbekistan; UzbekistánFil: Kumar, Mahesh. Indian Institute of Technology Jodhpur; Indi

Elucidating the enhanced photoelectrochemical performance of zinc-blende ZnS/wurtzite ZnO heterojunction and adsorption of water molecules by molecular dynamics simulations

ZnS-containing industrial waste (hereafter referred to as ZnS-IW) from the mining/metallurgy industry is modified with hydrothermally synthesized ZnO for study the enhancement of UV-light-induced photocurrent. The XRD, SEM and TEM results reveal that submicron-sized rod-like crystals of ZnO are deposited on large plate-like particles of ZnS-IW. Significant improvement in UV-induced photocurrent is reported for the 1:1 ratio photoanode (ZnS-IW:ZnO), ∼24 and ∼8 times compared to pristine ZnS-IW and ZnO, respectively, this measured at the potential that maximizes power density: 0.5 V vs. Ag–AgCl. The photocurrent response correlates well with the Gärtner-Butler theory and the formation of a ZnS-IW@ZnO heterojunction was supported by the positions of the valence and conduction bands, lifetime measurements and specific adsorption of water molecules. In fact, molecular modeling calculations indicate that the incorporation of ZnO leads to higher adsorption of water with the preferential formation of a monolayer, proving the synergetic effect due the heterojunction. The optoelectronic properties of these functional materials make them good candidates to support photocatalysis and light-sensing applications.Fil: Vargas Balda, Ronald Eduardo. Universidad Nacional de San Martin. Instituto Tecnologico de Chascomus. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - la Plata. Instituto Tecnologico de Chascomus.; Argentina. Universidad Simón Bolívar; VenezuelaFil: Madriz Ruiz, Lorean Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Universidad Simón Bolívar; VenezuelaFil: Márquez, Victor. Universidad Simón Bolívar; VenezuelaFil: Torres, Daniel. Universidad Simón Bolívar; VenezuelaFil: Kadirova, Zukhra C.. National University of Uzbekistan; UzbekistánFil: Yubuta, Kunio. Tohoku University; Japón. Kyushu University; JapónFil: Hojamberdiev, Mirabbos. Technishe Universitat Berlin; Alemani

Influence of BiOI content on the photocatalytic activity of Bi2WO6/BiOI/allophane composites and molecular modeling studies of acetaldehyde adsorption

As a major indoor volatile organic compound, acetaldehyde is considered to be toxic when applied externally for prolonged periods; it is an irritant and a probable carcinogen. In this work, Bi2WO6/BiOI/allophane (BW/BI/A) composites with different molar ratios of Bi2WO6:BiOI were prepared by either mechanical mixing or a hydrothermal synthesis. The adsorption capacity and photocatalytic activity of the prepared composites were evaluated for the adsorption and photodegradation of gaseous acetaldehyde in the dark and under visible light irradiation, respectively. SEM revealed that with increasing BiOI content, the overall morphology of the BW/BI/A composite was altered because BiOI nanoparticles gradually occupied the surfaces of the nanosheets, which formed flower-like structures, and eventually covered the surfaces of the Bi2WO6 particles. Adsorption affinities and preferential adsorption sites of acetaldehyde molecules on the Bi2WO6, BiOI, and allophane components of the BW/BI/A composite were also predicted using molecular dynamics simulations. The BW/0.5BI/A composite exhibited high adsorption capacity, excellent photocatalytic performance and good stability owing to its large specific surface area, greater number of easily accessible active sites, facilitated diffusion of reactants, multiple scattering of incident light, and formed p–n heterojunction, which suggest that it can be used in environmental remediation in the future.Fil: Hojamberdiev, Mirabbos. Nagoya University; Japón. Tokyo Institute of Technology; JapónFil: Kadirova, Zukhra C.. Tashkent Institute of Chemical Technology; UzbekistánFil: Makinose, Yuki. Shimane University; JapónFil: Zhu, Gangqiang. Shaanxi Normal University; ChinaFil: Matsushita, Nobuhiro. Tokyo Institute of Technology; JapónFil: Rodriguez, Juan. Universidad Nacional de Ingeniería; PerúFil: Aldabe, Sara Alfonsina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Hasegawa, Masashi. Nagoya University; JapónFil: Okada, Kiyoshi. Tokyo Institute of Technology; Japó

Unfolding the role of B site-selective doping of aliovalent cations on enhancing sacrificial visible light-induced photocatalytic H2 and O2 evolution over BaTaO2N

The doping of foreign cations and anions is one of the effective strategies for engineering defects and modulating the optical, electronic, and surface properties that directly govern the photocatalytic O2 and H2 evolution reactions. BaTaO2N (BTON) is a promising 600 nm-class photocatalyst because of its absorption of visible light up to 660 nm, small band gap (Eg = 1.9 eV), appropriate valence band-edge position for oxygen evolution, good stability under light irradiation in concentrated alkaline solutions, and nontoxicity. Although the photocatalytic and photoelectrochemical water-splitting efficiencies of BaTaO2N have been progressively improved, it is still far from the requirements set for practical applications. Here, we employ a 5% B site-selective doping of aliovalent metal cations (Al3+, Ga3+, Mg2+, Sc3+, and Zr4+) to enhance sacrificial visible light-induced photocatalytic H2 and O2 evolution over BaTaO2N. The results of physicochemical characterizations reveal that no significant change in crystal structure, crystal morphology, and optical absorption edge is observed upon cation doping. Therefore, the difference observed in O2 and H2 evolution during the photocatalytic reactions over pristine and doped BaTaO2N photocatalysts is explained by examining optical, electronic, and surface properties. Also, molecular dynamics (MD) is used to gain insights into the respective effect of cation doping on adsorption energy of water molecules and formed intermediates (H* for H2 evolution and HO*, O*, and HOO* for O2 evolution) on the BaTaO2N surfaces terminated with TaO6, TaN6, and TaO4N2 octahedra. Finally, the experimental reaction rates for H2 and O2 evolution are correlated well using a linear energy–performance relationship, elucidating the doping and surface-termination trends observed in the BaTaO2N photocatalysts.EC/H2020/793882/EU/Carbon-Oxynitride Coupled Artificial Photosynthesis System For Solar Water Splitting Beyond 600 nm/H2O-SPLI

Detoxifying SARS-CoV-2 antiviral drugs from model and real wastewaters by industrial waste-derived multiphase photocatalysts

The use of antiviral drugs has surged as a result of the COVID-19 pandemic, resulting in higher concentrations of these pharmaceuticals in wastewater. The degradation efficiency of antiviral drugs in wastewater treatment plants has been reported to be too low due to their hydrophilic nature, and an additional procedure is usually necessary to degrade them completely. Photocatalysis is regarded as one of the most effective processes to degrade antiviral drugs. The present study aims at synthesizing multiphase photocatalysts by a simple calcination of industrial waste from ammonium molybdate production (WU photocatalysts) and its combination with WO3 (WW photocatalysts). The X-ray diffraction (XRD) results confirm that the presence of multiple crystalline phases in the synthesized photocatalysts. UV–Vis diffuse reflectance spectra reveal that the synthesized multiphase photocatalysts absorb visible light up to 620 nm. Effects of calcination temperature of industrial waste (550–950 °C) and WO3 content (0–100%) on photocatalytic activity of multiphase photocatalysts (WU and WW) for efficient removal of SARS-CoV-2 antiviral drugs (lopinavir and ritonavir) in model and real wastewaters are studied. The highest k1 value is observed for the photocatalytic removal of ritonavir from model wastewater using WW4 (35.64 ×10–2 min–1). The multiphase photocatalysts exhibit 95% efficiency in the photocatalytic removal of ritonavir within 15 of visible light irradiation. In contrast, 60 min of visible light irradiation is necessary to achieve 95% efficiency in the photocatalytic removal of lopinavir. The ecotoxicity test using zebrafish (Danio rerio) embryos shows no toxicity for photocatalytically treated ritonavir-containing wastewater, and the contrary trend is observed for photocatalytically treated lopinavir-containing wastewater. The synthesized multiphase photocatalysts can be tested and applied for efficient degradation of other SARS-CoV-2 antiviral drugs in wastewater in the future.Fil: Hojamberdiev, Mirabbos. Technishe Universitat Berlin; AlemaniaFil: Czech, Bozena. Maria Curie-Skłodowska University; PoloniaFil: Wasilewska, Anna. Maria Curie-Skłodowska University; PoloniaFil: Boguszewska Czubara, Anna. Medical University of Lublin; PoloniaFil: Yubuta, Kunio. Kyushu University; JapónFil: Wagata, Hajime. Meiji University; JapónFil: Daminova, Shahlo S.. Tashkent State Technical University; UzbekistánFil: Kadirova, Zukhra C.. Tashkent State Technical University; UzbekistánFil: Vargas Balda, Ronald Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); Argentin